Water works for mild dehydration, but drinks containing electrolytes, particularly sodium, rehydrate you faster and help your body hold onto more fluid. The best choice depends on how dehydrated you are and what caused it.
Why Electrolytes Matter More Than Volume
Your small intestine absorbs water most efficiently when sodium and a small amount of glucose are present together. These two molecules activate a transport protein that pulls water through the intestinal wall, dramatically increasing the rate of fluid absorption compared to plain water alone. This is why every effective rehydration drink contains some combination of salt and sugar.
Research using a beverage hydration index, which measures how much fluid your body retains over several hours compared to water, consistently shows that drinks with electrolytes keep you hydrated 12 to 15 percent better than water alone. The electrolyte content matters more than added carbohydrates or protein for short-term fluid retention. A drink with electrolytes in the range found in typical sports drinks can maintain a positive fluid balance for up to four hours after drinking, while plain water drops below zero within two hours.
Best Drinks Ranked by Effectiveness
Oral Rehydration Solutions
Products like Pedialyte are the gold standard for correcting dehydration from illness, heat exposure, or hangovers. They contain two to three times the sodium of a standard sports drink and significantly more potassium, with far less sugar. A 12-ounce serving of Pedialyte Classic has about 9 grams of sugar and 16 percent of your daily sodium needs, compared to 22 grams of sugar and 17 percent of sodium in the same serving of Gatorade. That ratio of electrolytes to sugar is deliberately designed to match how your gut absorbs fluid most efficiently.
You can also make a basic oral rehydration solution at home: mix six teaspoons of sugar and half a teaspoon of salt into one liter of clean water. It won’t taste great, but it works.
Sports Drinks
Standard sports drinks like Gatorade are effective for rehydration during or after exercise, though they contain more sugar than you need for rehydration alone. Research shows that drinks combining carbohydrates with electrolytes produce faster fluid retention than electrolyte-only beverages in the first two hours. If you’re rehydrating after a workout, the extra calories may actually be welcome. If you’re rehydrating from illness and not burning calories, the sugar-free versions with added electrolytes are a better fit.
Milk
This one surprises most people. Low-fat milk consistently outperforms both water and sports drinks for fluid retention. Milk contains about 18 mmol/L of sodium and 38 mmol/L of potassium, plus roughly 36 grams of protein per liter. That protein turns out to be a major player: studies show milk protein accounts for about 56 percent of milk’s fluid retention advantage. The protein triggers a hormone called aldosterone that tells your kidneys to hold onto sodium, which in turn keeps water in your body longer. Milk also empties from the stomach more slowly, giving your intestines more time to absorb the fluid.
Coconut Water
Coconut water is naturally rich in potassium (roughly 51 mEq/L) and contains moderate amounts of sodium and chloride. In studies comparing it to sports drinks and plain water, coconut water performed equally well for rehydration and fluid retention. Its main advantage is that it’s a natural source of electrolytes without added sugars or artificial ingredients. The downside is that it’s relatively low in sodium compared to an oral rehydration solution, so it’s better for mild dehydration or everyday hydration than for recovering from significant fluid loss.
Plain Water
Water is fine for mild dehydration, especially if you’re also eating food that contains salt. The limitation is that your body doesn’t retain it as well as electrolyte-containing drinks. Your kidneys respond to a large intake of plain water by increasing urine output, so you lose a good portion of what you drink within a couple of hours. If you only have water available, drinking it alongside a salty snack helps your body hold onto more of it.
Drinks That Can Make Dehydration Worse
Sugary sodas, undiluted fruit juice, and energy drinks with high sugar content can actually pull water into your gut rather than absorbing it into your bloodstream. Fructose is one of the biggest offenders. It stimulates the intestines to release water and electrolytes, which can loosen stools and increase fluid loss. Apple juice, pear juice, and regular soda are particularly problematic when you’re already dehydrated, especially from a stomach bug. If you want to drink juice, dilute it with at least an equal part water.
Alcohol is a clear net negative. It suppresses the hormone that tells your kidneys to retain water, so you lose more fluid than you take in at any meaningful alcohol concentration.
Coffee and tea are a different story. Despite their reputation, caffeinated beverages at normal serving sizes don’t cause dehydration. Research shows that the caffeine in a standard cup or two of coffee or tea has no meaningful diuretic effect, especially if you drink them regularly. You’d need at least 250 to 300 mg of caffeine (roughly three cups of coffee) on a caffeine-free baseline to see any short-term increase in urine output. Your morning coffee still counts toward your fluid intake.
How Much and How Fast to Drink
Gulping a large amount of fluid all at once isn’t the best approach. Your stomach can only empty so fast, and drinking too quickly can cause nausea, especially if you’re already feeling unwell. For active rehydration, aim for about 200 to 300 mL (roughly 7 to 10 ounces) every 10 to 20 minutes. That pace matches your gut’s absorption capacity without overwhelming it.
After exercise or a bout of illness, try to correct your fluid deficit within two hours. A practical way to estimate how much you need after a workout is to weigh yourself before and after: each pound lost represents roughly 16 ounces of fluid you need to replace. Aim to drink about 150 percent of what you lost, since some of what you drink will be excreted before it’s absorbed. Including sodium in your recovery fluids stimulates thirst and helps your body retain more of what you take in.
When Drinking Isn’t Enough
Oral rehydration works for the vast majority of mild to moderate dehydration. About 96 percent of people, including children with gastroenteritis, can rehydrate successfully by mouth. But there are situations where drinking fluids can’t keep up with losses. Signs that oral rehydration is failing include vomiting three or more times after starting to drink, diarrhea or fluid loss that exceeds what you’re taking in, or no improvement in symptoms after 24 hours of steady fluid intake. In children, signs of worsening dehydration include no tears when crying, no wet diapers for several hours, or a sunken soft spot on an infant’s head.
Severe dehydration with confusion, rapid heartbeat, very low urine output, or fainting requires intravenous fluids. These situations need medical attention, not a better beverage choice.